2,5-Furan dicarboxylic acid (hereinafter also referred to as “FDCA”) is a useful compound as an intermediate product for fine chemicals or raw materials of synthetic resins, though the compound can be synthesized from fructose (fruit sugar) contained in a large amount in plants. For this reason, FDCA is selected as one of building block chemicals for biorefinery which have been identified by The US Department of Energy.
FDCA is highly practically valuable as a monomer for synthetic resins or toner binders or as an intermediate product in various application fields such as medicines, agricultural chemicals, insecticides, antibacterial agents, perfumes and others. Therefore, various studies have been made on the process for production of FDCA.
WO 2008/054804A discloses a method of oxidation of 5-hydroxymethylfurfural (hereinafter also referred to as “HMF”) in which oxygen is supplied into an aqueous solution of HMF to subject HMF to oxidation reaction at a temperature of from 50 to 200° C. under a pressure of from 150 to 500 psi (1.03 to 3.45 MPa) in the presence of a catalyst prepared by supporting Pt on a carrier such as ZrO2. 
In Onofre Casanova, et al., “ChemSusChem”, 2009, Vol. 2, p. 1138, there is disclosed a technology of oxidation reaction for conversion of HMF into FDCA in which HMF and oxygen are fed into an alkali aqueous solution having a pH of 8 to 11 to subject HMF to oxidation reaction in the presence of a catalyst prepared by supporting Au on a CeO2 carrier at 25° C. for 4 h, and then the resulting oxidation reaction product is heated to 130° C. and further reacted under 1.0 MPa for 3 h.
In addition, in Hicham Ait Rass, et al., “Green Chemistry”, 2013, Vol. 15, p. 2240, there is disclosed a selective aqueous phase oxidation method for transformation of HMF into FDCA in which HMF is subjected to air oxidation in an alkali aqueous solution having a pH of about 8 to about 11 in the presence of a catalyst prepared by supporting Pt and Bi on activated carbon at 100° C. under 40 bar (4.0 MPa).